Einstein@Home detects unusual stellar pair

Apr 07, 2011

Orbiting around a common centre of gravity: This simulation shows the orbits of pulsar J1952+2630 and its companion, presumably a white dwarf. The orbits are virtually circular, they only appear to be elliptical due to the viewing angle. The mass of the white dwarf, at 95 per cent of that of our Sun, is unusually high for such a binary system. Credit: AEI

(PhysOrg.com) -- Neutron stars are quite unique: the material they are made of is packed much more densely than conventional matter. They rotate extremely fast about their own axis, emitting radiation in the process, so they are often visible as pulsars in the radio spectrum. Researchers at the Max Planck Institute for Gravitational Physics in Hanover, working as part of the international PALFA Collaboration, and with the help of participants in the Einstein@Home project, have now discovered a pulsar accompanied by a white dwarf  a burnt-out star. The researchers want to weigh the pair, using what is known as the Shapiro effect.

When faced with tricky questions relating to the general theory of relativity, scientists usually look in the universe for answers. Even then, it is often very difficult to filter out the right astrophysical objects from the plethora of data. That is why scientists call on volunteers to help them in the time-consuming process of analysing data, making unused computing power on their home or office computers available for projects like Einstein@Home.

Armed with this support, the research group headed by Bruce Allen, Director at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI), Hanover, along with colleagues from the PALFA Collaboration, discovered radio pulsar J1952+2630. The researchers found it in data from the Arecibo telescope. "I'm very excited that the Einstein@Home team has discovered another exotic radio pulsar. These amazing objects are so extreme that if they were crushed to one-third of their size, they would collapse to form black holes. And a big ,thank you` to our thousands of volunteers: we'd be nowhere without their contributions," says Allen.

J1952+2630 flashes every 20.7 milliseconds, and is around 31,000 light-years from Earth. From the radio pulse modulation, the astronomers concluded that the pulsar has a partner star with at least 95 per cent of the Suns mass. These two celestial bodies revolve around their common centre of gravity, orbiting once every 9.4 hours in what are virtually perfect circles.

From the shape of their orbits, the astrophysicists can draw important conclusions as to what the companion is like and how it came to exist, even though they cant see it directly. It is probably a (relatively heavy) white dwarf  an expired star that was once quite ordinary, like our Sun. At the end of its life, it blew up into a red giant and cast off its outer layer of matter, some of which the neutron star then absorbed.

The two stars also exchanged (orbital) angular momentum, which is how they came to have perfectly circular orbits. Had this star formerly had a much greater mass than the Sun, then it, too, would have exploded into a supernova at the end of its life, and become a neutron star. The momentum generated in this process would have kicked it into an asymmetric elliptical orbit.

Astronomers currently know of 1,900 pulsars, single stars included.

The combination of a neutron star and a rather massive white dwarf orbiting one another in a perfect circle is rare. White dwarfs orbiting like this usually have a mass of just 10 to 30 percent of the mass of the Sun. And just half a dozen of the hundred or so known binary star systems with pulsars are like this.

Thanks to the relatively high mass of the companion, this binary star system will presumably be suited to testing a phenomenon of general relativity, namely the gravitational time delay of light, says Allens Ph.D. student Benjamin Knispel. Which means we could also determine the precise mass of each component.

This effect, also known as the Shapiro delay, occurs when visible light or radio waves pass through a gravitational field, for instance that of a star, on their way through the universe. The gravitational field diverts these beams from their straight path. But this means the light takes longer to make the detour. When the white dwarf moves into the line of sight between the pulsar and the Earth, the radio pulses which are emitted by the neutron star in regular intervals must travel further and further.

The pulses thus reach the observer at ever-increasing time intervals. To measure this, we need to look at the system from the side, if possible  that is, at the edge of the plane of orbit  so that, in certain configurations, the radio pulses from the neutron star pass through the white dwarfs gravitational field on their way to us, says Knispel. This method can be used to weigh the two stars. Knispel and his colleagues are already planning the next observations to do just that.

The pulsar ALFA (PALFA) Consortium was founded in 2003 with the aim of conducting a large-scale pulsar survey with the Arecibo telescope. It includes astronomers from 20 universities, institutes and observatories worldwide.

Einstein@Home, with more than 290,000 participants, is one of the largest distributed computing projects in the world. It was set up in 2005 and has been searching for gravitational waves amongst the data from the detectors of the international LIGO/Virgo/GEO collaboration. Since 2009, it has been using 35 per cent of its available computing power to support the work of the PALFA Collaboration.

The two amateur scientists whose computers found the strongest signal in the data analysis are Vitaly V. Shiryaev (Moscow, Russia) and Stacey Eastham (Darwen, Great Britain), who are credited by name and thanked in the publication.

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The atomic force does repel neutrons from another in the nucleus of an atom and will emit energy when disrupted, (He4), but is not a significant part of the fusion process of the Sun.

Indeed? Interesting, do you have a source for that?

I know that electrons are "repulsive" (degeneracy pressure) in white dwarfs via the Pauli exclusion principle (actually as I understand it all fermions are), but I've never heard of anything similar for neutrons.

on edit: ahhh I see that indeed neutrons are composite fermions. My assumption was incorrect.

Watching the first youtube link professor Manuel shares above, I can't help but cringe each time he talks and squeezes the syllables of "powered" into "parrd". Sitting in a year long course hearing that over and over, I'd shoot myself. Also, the speaking dichotomy of professor + Andrew elicits a feeling I'd normally get at a funeral.

The paper is here: http://arxiv.org/...40v1.pdf This seems like a very interesting system, and I hope someone does the work with a light bucket(and/or a radio telescope array) to find the pair in visible light. The current position is known to one minute of arc, (19h52m34:s4,+26deg30m14sec).My guess is that it will take work with the VLBA or the like to get the uncertainty down to under a second, before someone with a visual telescope can find the visual blinking. (And that will probably take work with a photometer.)

On a serious note electromagnetically neutral particles radiate so repulsion is present as long as electromagnetism is. When energy is not present there is no repulsion (like in a BEC), true BEC'a cannot exist, but if Energy disappeared the whole universe would fall into one singular point.

Omatumr is correct, neutron repulsion is very much real, ridicule all you like but the only way for neutron repulsion to cease is to remove energy from the neutron ( don't forget that a neutron in vacuum quickly becomes a proton and electron ).

The Gravitational Time Delay, now known as the Shapiro Effect, was first predicted by Einstein. It is proven by measuring the time delay of radar and radio beams sent between Earth and Mars. As the beams pass closer and closer to the Sun, a delay in the transit time is measured. This delay is caused by the gravitational force of the Sun (Distortion of space time). This delay also causes a Doppler shift in the signal, which is equivalent to the redshift observed for distant galaxies....

Oliver won't answer the question. Yet he clearly has an opinion on it and HE is the expert since he is nearly the only person that believes in HIS neutron repulsion. I seriously doubt the students that did the work have ever said anything to support him. He sure hasn't used any paper of theirs written after that one for support.

On a serious note electromagnetically neutral particles radiate so repulsion is present as long as electromagnetism is.

Radiate what? They are electromagnetically neutral overall and the variation of charge within a neutron is minimal since the positions of the quarks overlap due to Uncertainty. There is supposed to be a tiny bit of charge separation.

but if Energy disappeared the whole universe would fall into one singular point.

There would nothing to fall and no gravity. Mass and energy are equivalent.

Horse manure. The Pauli Exclusion Principle is as real as things get in physics and it fits Oliver's data. Oliver can't even tell us whether the alleged force is long range or not. If he can't manage that than he has no evidence of the alleged force.

And he refuses to say what differentiates his force from the Pauli Exclusion Principle. All indications are the he never heard of it till it was brought up on one forum or another. He still hasn't acknowledged the question. On many forums he would be banned for that.

don't forget that a neutron in vacuum quickly becomes a proton and electron ).

Half life is about 11 minutes. Now where is some evidence to support the idea and what separates it from the PEP.

I watched the youtube link and I didn't know whether to cry or laugh at 3:56 in particular.

-How do you know that neutron repulsion caused the [nuclear] bomb to explode?-Well Andrew, adding a single neutron to the uranium nucleus is what triggered the explosion that produced the fission event.

Did you just say that the first neutron did not itself split an atom? Or did you mean to say that the first neutron triggered the fission event which caused the chain reaction? If the latter you're just full of nonsense. The fact that one triggers uranium fission with a neutron has nothing to do with "neutron repulsion." That's just a bullshit correlation argument aimed at the same people who will swallow the other pseudoscience crap such as "The Secret" and you know it.

Omatumr is correct, neutron repulsion is very much real, ridicule all you like but the only way for neutron repulsion to cease is to remove energy from the neutron (don't forget that a neutron in vacuum quickly becomes a proton and electron ).

Thanks for your comment. As pointed our earlier in other PhysOrg.com sites,

1. Weak long-range forces become strong at short distances, and strong short-range forces become weak at long distances. Either/or views of nature are not insight, but a handicap.

2. Personal attacks from those who hide their own identity are like actions of the Communist Youth League in the old USSR who supported Lysenkoism:

A self-sustainable cult-like system of distortions, omissions, and lies designed to support faulty or fraudulent research of "politically correct" pseudo-scientists.

Yes I do know how many choices you have and which. Do you want a lesson in elementary physics?

BTW stamping your feet and saying something is an empirical fact doesn't actually make it a fact. You're entitled to your own OPINIONS, but not your own FACTS. The FACT is that neutrons are not repulsive at all, but exert degeneracy pressure against one another via the PEP.

At close distances neutrons are very energetic, neutron stars are pretty densely packed, neutrons are not influencing each other with positive or negative attraction, derivable to positron and electron respectively, the neutrons are influencing each other by their decay, photons, gamma ray bursts is what we see in pulsars, photons are force carriers of electromagnetism, decay is negative and positive energy. Neutrons influence neutrons by photons, so all that garbage is false, but not relativistically, on earth pressures are not sufficient to cause neutrons to act in such a powerful way, but we can see them acting, we know the potential.

Neutron neutron repulsion is real, and it is electromagnetism that is causing it.